Round shaking-grate.



No. 699,378. Patented May 6, I902.

F. W. FOSTER.

ROUND SHAKING GRATE.

(Application filed Dec. 2, 1901.) (N 0 M ed el.)

3 Sheets-Sheet l.

Ehrfiassgs: I fNJ N W No. 699,378. Patented May 6, I902.

F. W; FOSTER.

ROUND SHAKING GRATE.

(Application filed Dec. 2, IQOL) (No Model.) 3 Sheets-Sheet 2.

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No. 699,378. Patented May 6, I902.

F. W. FOSTER.

ROUND SHAKING GBATE. LApplicatian filed Dec. 2, 1901.)

(I0 Model.) 3 Sheets-$heet 3.

UNlT ED STATES PATENT @FFICE.

FRANK \V. FOSTER, OF MELROSE, MASSACHUSETTS.

ROUND SHAKlNG-GRATE I.

SPECIFICATION forming part Of Letters Patent N 0. 699,37 8, dated May 6, 1902.

Application filed December 2, 1901. Serial No. 84,357. (No model.)

To all whom it may concern.-

Be it known that I, FRANK W. FOSTER, a citizen ofthe United States, and a resident of Melrose, in the county of Middlesex and State of Massachusetts, have invented new and useful Improvements in Round Shaking-Grates, of which the following is a specification.

My invention relates to shaking-grates; and it consists of improvements in their structure whereby all the advantages peculiar to shaking grate-bars and usually obtained in a square grate are secured in a round grate, such as is commonly placed underan upright tubular boiler.

In the drawings hereto annexed,which illus trate an embodiment of my invention, Figure 1 is a top plan view of a round boiler-grate whereon part of the grate-bars are removed and part broken away to exhibit the structure of the lower portion. Fig. 2 is a top plan view of part of one of the grate-bars of the grate shown in Fig. 1 broken off near the middle thereof, as shown in the upper half of Fig.1. Fig. '3 is a side elevation of the grate shown in Fig. 1. grate; and Figs. 5 and 6 are views in plan and elevation, respectively, of one member of the ring-frame of the grate.

My improved round boiler-grate comprises a frame with rocker-bars pivotally mounted thereon, which engage with movable gratebars supported on the frame and circumferential extension-pieces which afiord fire-supporting surfaces at the circumference of the grate beyond the reach of the ends of the movable grate-bars. The grate-bars B, Fig. 1, are straight bars extending across the frame in such manner that each bar on one side of a diametrical division between the two middle bars finds its duplicate on the other side.

The grate-bars, which occupy one-half of the circular space of the grate, diminish step by step in length and occupy as much of the entire surface of the grate as is practicable, allowing for the longitudinal vibration of each bar. Around the circumference of the the supporting surface the spaces which in the nature of things cannot be occupied by movable grate-bars are filled with extensionpieccs D,'which, together with the movable bars, are supported upon the grate-frame.

bars, brackets A and legs A", Fig. 3.

Fig. 4 is a cross-section of the same- The frame of the grate is composed of segmental curved bars A and straight chord-bars A, which are bolted to the ends of the curvfid T e curved bars A in the construction herein shown are four in number, arranged in pairs, which are suitably bolted together, and are provided with depending hangers A Figs. 4 to 6, to which the chord-bars A are bolted, the chord-bars thus occupying a level lower than the curved bars A. Supports for the outermost movable grate-bars and the end extension-pieces which adjoin the said bars are provided in the shape of brackets A", which are bolted to and extend outward and upward from the chord-bars A. Upon the upper edge of the curved bars A are notches A which serve as supports and guides for the movable grate-bars, and secured to or cast integral with the curved bars A and brackets A are the sockets D, which provide for the circumferential extension-pieces D.

Rocker-bars G extend diametrically across the grate at right angles to the movable gratebars and are pivotally supported at their ends upon the chord-bars A. The rocker-bars C are duplicates and either one may serve in the place of the other merely by being turned end for end in the frame. Rocker-heads G extend upward from the rocker-bars (J and are so disposed thereon that the rocker-heads in one bar stand opposite to the spaces between the rocker-heads of the other bar. At (1 the rocker-bars are joined to links G which are articulately connected to the rocker-handles C The grate-bars B are of skeleton form, provided with longitudinal webs B and branches B extending therefrom. At intervals opposite branches B are joined together, so as to form the transverse webs or ties B The rocker-heads C engage with the webs B of the grate-bars. These webs on each grate-bar are suitably notched at a point a little at one side of the middle of the bar, so that any grate-bar is susceptible of engagement with either rocker-bar by turning the grate-bar end for end. The circumferential extensionpieces D consist of open grills having fingers D, which interlock with the end fingers B of the movable grate-bars. The extensionpieces D are provided with suitable depending stems, which engage with the sockets D Segmental side pieces D fill the outermost circumferential space not provided for either by the movable grate-bars or the circumferential extension-pieces D.

In aboiler-grate such as the one herein illustrated there is invariably a stronger draft at the middle of the grate than at the circumferential portion, and in order to insure a uniform fire I have provided an arrangement by which the inequalities of draft are compensated for.

In Fig. 2, Where half of one of the bars of my improved grate is shown in plan, it will be observed that the air-spaces 13' between the fire-supporting branches B are smaller at the middle of the grate-bar than they are at its outer end.

I so proportion the grate-bar and its firesupporting parts that the ratio between firesupporting iron and air-space changes progressively from the middle to the circumference of the grate, this ratio being greater at the middle than at the circumference. Thus in Fig. 2, which represents part of one of the middle bars of my grate, a length occupied by five branches B as at b, will be occupied by only three such branches at b and by four branches half-way between I) and b. I carry out this gradation of effective air-space from the middle of the grate outward in all directions, and by this means compensate for the greater natural draft at the center of the grate and assist the stokcr in keeping an even fire.

2. In a round boiler-grate, the combination with a ring-frame comprising straight chord members and side brackets projecting from said chord members, parallel grate-bars supported at the ends in the frame and at the middle by rocker-bars, the outer grate-bars resting in the said side brackets, the rockerbars, pivotally hung on the frame, and an annular fire-supporting surface made in sections, filling the space between the ends of the grate-bars and the fire-box wall, and supported by the ring-frame.

3. In a round boiler-grate, the combination of parallel grate-bars supported by a frame, the frame, consisting of ring-segments, hangers depending from the ring-segments, chordbars secured to the hangers at a level below that of the ring-segments, and rocker-bars hung on the chord-bars, and connected to the grate-bars, substantially as described.

Signed by me at Boston, 1VIassachusetts,this 25th day of November, 1901.

v FRANK WV. FOSTER.

Witnesses:

' ROBERT CUSHMAN,

FRANK S. IIARTNETT. 

